Ch. 17 PET

Which of the following radionuclides is not a positron emitter? 

(a) 82Rb 

(b) 15O 

(c) 18F 

(d) 14C 

(e) 68Ga 

(d) 14C 

When a neutron-deficient nucleus emits a positron: 

(a) Atomic mass number decreases by 1. 

(b) Atomic mass number increases by 1. 

(c) Atomic number increases by 1. 

(d) Atomic mass number is unchanged. 

(d) Atomic mass number is unchanged. 

Which of the following has the shortest half-life? 

(a) 82Rb 

(b) 13N 

(c) 15O 

(d) 18F 

(a) 82Rb 

Which of the following will not affect the distribution of 18F-FDG on a PET image? 

(a) Intense physical activity the day before imaging. 

(b) Serum insulin level. 

(c) Serum glucose level. 

(d) Bladder catheterization. 

(e) All of the above affect distribution. 

(e) All of the above affect distribution. 

Normal 18F-FDG distribution would show the least activity in the: 

(a) Brain 

(b) Bone 

(c) Bladder 

(d) Myocardium 

(b) Bone 

All positron-emitting isotopes are produced in a cyclotron. 

(a) True 

(b) False 

(b) False 

18F-FDG-PET is not an important tool for: 

(a) Restaging of colorectal cancer 

(b) Monitoring response to treatment of non-Hodgkin’s lymphoma 

(c) Detecting Helicobacter pylori 

(d) Imaging metastases in breast cancer 

(c) Detecting Helicobacter pylori 

Which of the following is true regarding 18F-FDG? 

(a) Its distribution in the brain is related only to blood flow. 

(b) It is a potassium analog. 

(c) It has a half-life of 60 min. 

(d) It is taken up by disease-free myocardium. 

(d) It is taken up by disease-free myocardium. 

18F-FDG-PET images show a map of the _____ distribution in the body. 

(a) Oxygen 

(b) Insulin 

(c) Glucose 

(d) Potassium 

(c) Glucose 

What length of time should a lactating female who undergoes 18F-FDG-PET scanning wait before resuming breastfeeding? 

(a) 4 h 

(b) 24 h 

(c) 1 week 

(d) Breastfeeding should be discontinued 

(b) 24 h 

Because of the relatively high energy of the photons detected in PET imaging, attenuation correction does not need to be performed. 

(a) True 

(b) False 

(b) False 

What part of a PET scanner quality control regimen is necessary for the computation of attenuation factors? 

(a) Coincidence timing calibration 

(b) Normalization correction 

(c) PMT gain adjustment 

(d) Blank scan 

(d) Blank scan 

Which of the following describes a random coincidence? 

(a) The simultaneous detection of annihilation photons originating from a single positron 

(b) The simultaneous detection of annihilation photons originating from a single positron although one of the photons has been scattered before reaching the detector 

(c) The simultaneous detection of photons originating from different positrons 

(c) The simultaneous detection of photons originating from different positrons 

Which of the following is not a scintillation crystal found in PET cameras: 

(a) Lutetium oxyorthosilicate (LSO) 

(b) Bismuth germanate (BGO) 

(c) Lead sulfate (PbSO₄) 

(d) Gadolinium oxyorthosilicate (GSO) 

(c) Lead sulfate (PbSO₄) 

PET images may be reconstructed using: 

(a) Coincidence detection 

(b) Filtered back projection 

(c) K-space filling 

(d) Block detection 

(b) Filtered back projection 

Following a positron annihilation, two 511 keV photons are emitted in opposite directions. If one of the photons is deflected in the body: 

(a) Only the unscattered photon will contribute to the image. 

(b) The deflected photon may be detected outside the correct LOR. 

(c) The LOR may contain an angle. 

(d) The deflected photon will have a higher energy than the undeflected photon. 

(b) The deflected photon may be detected outside the correct LOR. 

A patient has undergone myocardial PET scans using 13N ammonia and 18F-FDG. There is little inferoapical activity on the ammonia scan, but there is homogeneous uptake in the same area on the FDG images. This suggests that: 

(a) An incorrect dose of 13N has been administered. 

(b) The inferoapical area may revascularize. 

(c) There is little viable tissue in the inferoapical wall. 

(d) The system requires a quality control check. 

(b) The inferoapical area may revascularize. 

Patient A and Patient B are injected with the same dose of 13N ammonia for a myocardial PET scan. The patients are of the same height, but Patient A weighs 120 lbs. while Patient B weighs 180 lbs. From which patient would more true coincidences be detected? 

(a) Patient A 

(b) Patient B 

(a) Patient A 

Chewing gum between injection of 18F-FDG and PET scanning will have no effect on the resulting images. 

(a) True 

(b) False 

(b) False 

Why is it important to know if a patient has an inflammatory condition before performing an 18F-FDG-PET scan? 

(a) 18F-FDG and certain anti-inflammatory medications cause severe reactions when used simultaneously. 

(b) 18F-FDG can exacerbate inflammatory conditions. 

(c) Some inflammatory conditions cause areas of increased uptake of 18F-FDG. 

(c) Some inflammatory conditions cause areas of increased uptake of 18F-FDG. 

Patient preparation for an 18FDG-PET scan of the whole body includes: 

(a) NPO the day before imaging 

(b) Fasting state of at least 4–6 h prior to injection 

(c) Encouraging intense physical activity the day before imaging 

(b) Fasting state of at least 4–6 h prior to injection 

18F-FDG is useful for imaging tumors because: 

(a) It is a glucose analog. 

(b) There is an elevated rate of glycolysis in tumors. 

(c) It becomes trapped in tumor cells. 

(d) All of the above. 

(d) All of the above. 

Which dose and route of administration are the best choices when performing a whole-body PET scan with 18F-FDG and a dedicated PET scanner? 

(a) 2–4 mCi IV 

(b) 2–4 mCi IM 

(c) 10–20 mCi IV 

(d) 10–20 mCi IM 

(e) 30–35 mCi IV 

(c) 10–20 mCi IV 

Fill in the blank. High blood glucose levels may _____ 18F-FDG uptake in tumors. 

(a) Decrease 

(b) Increase 

(a) Decrease 

Relative to one another, 82Rb and 82Sr are: 

(a) Isobars 

(b) Isotopes 

(c) Isotones 

(d) None of the above 

(a) Isobars 

What determines the lower limit of spatial resolution in PET scanners? 

(a) Timing window 

(b) Detector type 

(c) Positron range 

(d) Compton scatter 

(c) Positron range 

Parenteral nutrition should be discontinued for several hours prior to 18FDG imaging. 

(a) True 

(b) False 

(a) True 

Two unrelated annihilation photons are detected within the timing window and judged to be in coincidence. This is called a: 

(a) True coincidence 

(b) Random coincidence 

(c) Scatter coincidence 

(b) Random coincidence 

Noncolinearity refers to: 

(a) Annihilation photons that are not emitted at exactly 180° to one another due to particle momentum 

(b) The detection of two annihilation photons, at least one of which has been redirected by Compton scatter 

(c) The distance a positron travels before undergoing annihilation 

(a) Annihilation photons that are not emitted at exactly 180° to one another due to particle momentum 

On an 18F-FDG-PET scan of the whole body, muscle uptake can be decreased by: 

(a) Administering diazepam before injection of 18F-FDG 

(b) Maintaining the patient in the supine position during uptake 

(c) Minimizing chewing, talking, and swallowing during uptake 

(d) All of the above 

(e) (a) and (b) only 

(d) All of the above 

Dedicated PET scanners use: 

(a) Flat-field collimation 

(b) Electronic collimation 

(c) Converging collimation 

(d) No collimation 

(b) Electronic collimation 

Standardized uptake values are useful for: 

(a) Differential diagnosis of tumor type 

(b) Assessing tumor size changes 

(c) Assessing response to treatment 

(c) Assessing response to treatment 

A patient presents for PET scanning with 18FDG for suspected tumor of the left axilla. Which injection site should be avoided? 

(a) Right antecubital vein 

(b) Left antecubital vein 

(c) Right foot 

(d) Left foot 

(b) Left antecubital vein 

The recommended dose of gallium-68 DOTATATE (Netspot®) is: 

(a) 0.054 mCi/kg, up to 5.4 mCi 

(b) 10 mCi 

(c) 1 mCi 

(d) 25 mCi 

(a) 0.054 mCi/kg, up to 5.4 mCi 

F-18 PSMA is a PET imaging agent for patients with ________. 

(a) Breast cancer 

(b) Lung cancer 

(c) Prostate cancer 

(c) Prostate cancer 

Indications for performing Netspot® PET imaging are: 

(a) Localization of somatostatin receptor-positive neuroendocrine tumors 

(b) Prostate cancer 

(c) Breast cancer 

(d) Lung cancer 

(a) Localization of somatostatin receptor-positive neuroendocrine tumors 

Axumin (fluciclovine F-18) is a PET imaging tracer used to image: 

(a) Breast cancer 

(b) Prostate cancer 

(c) Lung cancer 

(d) Infection 

(b) Prostate cancer 

What is the administration method for F-18 PSMA? 

(a) Intravenous 

(b) Intramuscular 

(c) Oral 

(d) Inhalation 

(a) Intravenous 

Imaging with fluciclovine F-18 (Axumin) should be initiated: 

(a) 3–5 min postinjection 

(b) 30 min postinjection 

(c) 60 min postinjection 

(d) 90–120 min postinjection 

(a) 3–5 min postinjection 

Netspot® can be used to image both pediatric and adult patients. 

(a) True 

(b) False 

(a) True 

Typical dose of F-18 PSMA is: 

(a) 15 mCi 

(b) 9 mCi 

(c) 12 mCi 

(d) 5 mCi 

(b) 9 mCi 

What is the delay time between injection and scanning with F-18 PSMA? 

(a) Immediate postinjection 

(b) 15 min postinjection 

(c) 60 min postinjection 

(d) 2 h postinjection 

(c) 60 min postinjection 

Ga-68 DOTATATE is generator produced. 

(a) True 

(b) False 

(a) True 

The typical dose of fluciclovine F-18 is: 

(a) 10 mCi 

(b) 15 mCi 

(c) 20 mCi 

(d) 25 mCi 

(a) 10 mCi 

There are no contraindications to using Axumin (fluciclovine F-18). 

(a) True 

(b) False 

(a) True 

Patient preparation includes being NPO prior to the F-18 PSMA injection. 

(a) True 

(b) False 

(b) False 

Ga-68 DOTATATE PET imaging, from skull to mid-thigh, can be acquired: 

(a) Immediately postinjection 

(b) 15 min postinjection 

(c) 40–90 min postinjection 

(d) 2–4 h postinjection 

(c) 40–90 min postinjection 

Tumors that do not bear somatostatin receptors will not be visualized. 

(a) True 

(b) False 

(a) True 

F-18 PSMA is used to scan the female patient population. 

(a) True 

(b) False 

(b) False 

The half-life of Ga-68 DOTATATE is: 

(a) 68 min 

(b) 110 min 

(c) 6 h 

(d) 78.3 h 

(a) 68 min 

Patient should be encouraged to increase hydration prior to the study and to increase frequency of voiding after the administration of F-18 PSMA. 

(a) True 

(b) False 

(a) True 

Ga-68 DOTATATE PET should be performed prior to administering long-acting somatostatin analogs. When can short-acting analogs be used? 

(a) Up to 24 h before 

(b) 2 weeks before 

(c) Never 

(d) Time does not matter 

(a) Up to 24 h before 

How is Ga-68 DOTATATE administered? 

(a) Oral 

(b) Intravenous 

(c) Intramuscular 

(d) Inhalation 

(b) Intravenous